I have implemented custom itempanel for gridview to support variable item height using this link posted by JerryNixon.My Custom panel supports 3 different sized template(dep
Finally we implemented virtualized custom grdiview by referring to the code posted in this link. Code given in the link is for virtualizing horizontal gridview. I changed the code a bit to change it to vertical gridview. Many thanks to the person who posted the code. It helped a lot